The present invention relates, in general, to semiconductor devices and a method of manufacturing such devices and, more particularly, to a semiconductor device having a substrate on one surface of a semiconductor chip, the substrate extending on the chip so as to exceed the outside edge of the chip, thus carrying an increased number of solder balls or signal input/output terminals on the device and being almost free from being bent, and effectively dissipating heat from the chip to the atmosphere, the invention also relating to a method of manufacturing such a semiconductor device.
As is well known to those skilled in the art, a semiconductor device is used for mounting a semiconductor chip on a mother board in addition to intermediating input/output signals between the chip and the mother board. In accordance with the recent trend of compactness, lightness, thinness and smallness of semiconductor chips, it has been necessary to make the semiconductor device compact, light, thin and small.
FIG. 1 shows a conventional semiconductor device 100xe2x80x2. In the drawing, the semiconductor device 100xe2x80x2 is shown while being inverted for ease of description.
As shown in the drawing, the conventional semiconductor device 100xe2x80x2 comprises a semiconductor chip 40xe2x80x2, having a plurality of signal input/output pads or edge pads 41xe2x80x2 on its upper edge. A substrate 10xe2x80x2 is formed on the upper surface of chip 40 as follows. A polyimide layer 12xe2x80x2 is attached to the upper surface of the chip 40xe2x80x2 with an adhesive layer 21xe2x80x2 being interposed between the chip 40xe2x80x2 and the polyimide layer 12xe2x80x2. The above substrate 10xe2x80x2 also comprises a plurality of circuit patterns formed on the polyimide layer 12xe2x80x2. Each of the circuit patterns consists of a solder ball land 15xe2x80x2. A connector 14xe2x80x2 extends from the solder ball land 15xe2x80x2 and has a lead 13xe2x80x2 at its outside end, and is connected to an associated signal input/output pad 41xe2x80x2 of the chip 40xe2x80x2 at the lead 13xe2x80x2 using an electric connecting means 50xe2x80x2. A cover coat 16xe2x80x2 is coated on both the connectors 14xe2x80x2 of the above circuit patterns and the upper surface of the polyimide layer 12xe2x80x2. In order to protect the pads 41xe2x80x2 of the chip 40xe2x80x2, the electric connecting means 50xe2x80x2 and the leads 13xe2x80x2 from the atmospheric environment, the upper edge of the chip 40xe2x80x2 is packaged using a packaging material, thus forming a packaging part 60xe2x80x2. A solder ball 70xe2x80x2 is welded to each of the solder ball lands 15xe2x80x2 and is used for mounting the semiconductor device 100xe2x80x2 on a mother board.
Such semiconductor devices 100xe2x80x2 may be produced as follows. In a first conventional process, a plurality of semiconductor chips are primarily attached to the lower surface of a wafer-shaped substrate using an adhesive layer, thus performing a wafer lamination step. Thereafter, an electric connection step is performed. In the electric connection step, each signal input/output pad of each of the semiconductor chips is connected to an associated lead of the circuit patterns of the substrate using an electric connecting means. The electric connection step is followed by a packaging step wherein the upper edge of each of the semiconductor chips is covered with a packaging part so as to protect the electric connection part, comprising the signal input/output pads, the electric connecting means and the leads, from the atmospheric environment. Thereafter, a solder ball welding step, wherein a plurality of solder balls are welded to the solder ball lands of the substrate, is performed. A singulation step follows the solder ball welding step. In the singulation step, the wafer, with the substrate, is divided into a plurality of semiconductor devices.
Alternatively, the semiconductor devices may be produced through a second process. In the second process, a plurality of semiconductor chips are bonded to a rectangular or regular square substrate strip prior to performing the same electric connection step, packaging step, solder ball welding step and singulation step as that described for the first process.
In recent years, it is necessary to carry an increased number of signal input/output pads on a semiconductor chip in accordance with a development in the semiconductor chip integration technology. Therefore, it is also necessary to increase the number of solder balls formed on each semiconductor device. However, since the conventional substrate is formed on a limited area of one surface of a semiconductor chip as described above, the area of the substrate is smaller than that of the chip. This limits both the number of circuit patterns and the number of solder balls formed on each substrate.
In order to overcome the above-mentioned problems, the substrate may extend in a way such that it exceeds the outside edge of the chip. However, since the substrate is made of a flexible material, the enlarged substrate is partially and easily bent at a portion outside the edge of the chip. When a solder ball is carried on the portion of the substrate outside the edge of the chip, the substrate regrettably fails to firmly or effectively support the solder ball on that portion.
Another problem, experienced in the conventional semiconductor device, resides in that the device fails to effectively dissipate heat from the semiconductor chip into the atmosphere during an operation of the device. That is, in accordance with the recent trend of high integration degree and high operational frequency of semiconductor chips, each semiconductor chip emits a large quantity of heat during an operation of the device. However, the conventional semiconductor device does not have any structure designed to effectively dissipate the heat to the atmosphere, thus being reduced in its electric performance and causing an operational error of the chip.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a semiconductor device, of which the substrate extends on one surface of a semiconductor chip so as to exceed the outside edge of the chip and has an area larger than that of the chip, thus effectively carrying an increased number of circuit patterns and solder balls or signal input/output terminals on the device.
Another object of the present invention is to provide a semiconductor device, of which the electric connection part, comprising the bond fingers of the substrate and the signal input/output pads of the chip, is primarily packaged with a packaging material, thus being prevented from unexpected separation during a process of manufacturing the device, and which is secondarily packaged with a packaging material so as to enhance the bonding strength between the chip and the substrate, thus preventing an undesirable bending of the substrate and firmly supporting the solder balls carried on the substrate, and increasing the bonding strength at the junction between the parts of the device.
A further object of the present invention is to provide a semiconductor device which more effectively and quickly dissipates heat from the semiconductor chip into the atmosphere, thus being almost free from a reduction in its electric performance and being almost free from any operational error of the chip.
Still another of the present invention is to provide a method of manufacturing the above-mentioned semiconductor device.
In order to accomplish the above objects, an embodiment of the present invention provides a semiconductor device, comprising: a semiconductor chip having a plurality of signal input/output pads on one surface thereof; a substrate having a plurality of regularly arranged circuit patterns and an area larger than that of the semiconductor chip, each of the circuit patterns consisting of a solder ball land and a bond finger extending from the solder ball land, with a cover coat covering the circuit patterns except for an area corresponding to both the solder ball lands and the bond fingers, the substrate also having a hole at a position around the bond fingers; an adhesive layer adapted for bonding the substrate to the semiconductor chip with the signal input/output pads being exposed to an outside of the substrate through the hole of the substrate; electric connection means for electrically connecting each of the bond fingers of the substrate to an associated signal input/output pad of the chip, the electric connection means passing through the hole of the substrate; a primary packaging part adapted for packaging both the electric connection means and the signal input/output pads positioned inside the hole of the substrate; a second packaging part adapted for packaging an, area defined between a sidewall of the semiconductor chip and the substrate; and a solder ball welded to each of the solder ball lands provided on the substrate.
In the above semiconductor device, a polyimide layer may be formed between the adhesive layer and the circuit patterns.
In addition, a metal core layer may be formed between the polyimide layer and the adhesive layer.
The primary packaging part is preferably made of a liquid packaging material, while the second packaging part is preferably made of an epoxy molding compound.
In the present invention, the sidewall of the second packaging part may be aligned with the edge of the substrate.
The sidewall of the second packaging part may be positioned inside the edge of the substrate.
The sidewall of the second packaging part may be parallel to the sidewall of the semiconductor chip, or may be inclined downwardly relative to the sidewall of the semiconductor chip at an acute angle.
The surface of the semiconductor chip opposite to the surface having the signal input/output pads may be leveled with the surface of the second packaging part opposite to the substrate contact surface of the second packaging part.
In addition, a heat dissipating plate may be attached to the surface of the semiconductor chip opposite to the surface having the signal input/output pads.
The sidewall of the heat dissipating plate is covered with the second packaging part.
The surface of the heat dissipating plate opposite to a chip contact surface of the plate is leveled with the surface of the second packaging part opposite to the substrate contact surface of the second packaging part.
The electric connection means is preferably selected from a conductive wire and a lead.
In an embodiment of present invention, the circuit patterns comprise: a plurality of first circuit patterns formed on the substrate at a position corresponding to the surface of the semiconductor chip; and a plurality of second circuit patterns formed on the substrate at a position outside the edge of the semiconductor chip, with the hole being formed between the first and second circuit patterns while separating the first and second circuit patterns from each other.
The first packaging part may pass through the hole of the substrate prior to being brought into contact with the second packaging part.
The second packaging part may package an area defined between the second circuit patterns and the sidewall of the semiconductor package, thus supporting the substrate having the second circuit patterns thereon.
The signal input/output pads are arranged along opposite edges of the semiconductor chip.
An embodiment of present invention also provides a method of manufacturing a semiconductor device, comprising the steps of: preparing a substrate having upper and lower surfaces and a plurality of regularly arranged circuit patterns, each of the circuit patterns having upper and lower surfaces and consisting of a solder ball land and a bond finger extending from the solder ball land, with a cover coat covering the circuit patterns except for an area corresponding to both the solder ball lands and the bond fingers, the substrate also having a hole at a position around the bond fingers; bonding a semiconductor chip, having both an area not larger than of the substrate and a plurality of signal input/output pads, to the substrate using an adhesive layer in a way such that the signal input/output pads are exposed to an outside of the substrate through the hole of the substrate; electrically connecting each of the circuit patterns of the substrate to an associated signal input/output pad of the chip using an electric connection means passing through the hole of the substrate; primarily packaging both the electric connection means and the signal input/output pads positioned inside the hole of the substrate, thus forming a primary packaging part; secondarily packaging an area defined between a sidewall of the semiconductor chip and a lower surface of the substrate, thus forming a second packaging part; and welding a solder ball to each of the solder ball lands provided on the substrate.
In the above method, the substrate may further comprise a polyimide layer formed on the lower surface of the circuit patterns.
The above polyimide layer may be formed on a metal core layer.
An embodiment of the circuit patterns comprise: a plurality of first circuit patterns formed on the substrate at a position corresponding to the surface of the semiconductor chip; and a plurality of second circuit patterns formed on the substrate at a position outside the edge of the semiconductor chip, with the hole being formed between the first and second circuit patterns.
The second packaging part allows the lower surface of the semiconductor chip to be exposed to the atmosphere.
In the above method, the second packaging step may be performed with a heat dissipating plate being positioned on a lower surface of the semiconductor chip.
The first and second packaging steps may be performed while allowing the first packaging part to be brought into contact with the second packaging part.
The second packaging step may be performed so as to allow the second packaging part to package the area defined between the second circuit patterns and the sidewall of the semiconductor package, thus supporting the substrate having the second circuit patterns thereon.
In the above method, the electric connection means may be selected from a conductive wire and a lead.
In accordance with an embodiment of the present invention, the substrate, having an area larger than that of a semiconductor chip, is bonded to one surface of the chip and extends so as to exceed the edge of the chip, thus carrying an increased number of circuit patterns and an increased number of solder balls.
In addition, a second packaging part is formed on an area defined between the sidewall of the semiconductor chip and the lower surface of the substrate exceeding the edge of the chip. The portion of the substrate, exceeding the edge of the chip, is thus firmly supported by the second packaging part and is prevented from being bent. The second packaging part also firmly supports the solder balls welded to the upper surface of the substrate.
The semiconductor device of this invention is also designed to dissipate heat from the semiconductor chip into the atmosphere through the lower surface of the chip or through a heat dissipating plate mounted to the lower surface of the chip. Therefore, the semiconductor device is almost completely free from a reduction in the electric performance of the chip or an operational error of the chip during an operation.